1. Field of the Invention
The present invention generally relates to rotary vane pumping machines, and more particularly, a rotor and stator cooling system for a rotary vane pumping machine.
2. Description of the Related Art
The overall invention relates to a large class of devices comprising all rotary vane (or sliding vane) pumps, compressors, engines, vacuum-pumps, blowers, and internal combustion engines. Herein the term pumping machine refers to a member of a set of devices including pumps, compressors, engines, vacuum-pumps, blowers, and internal combustion engines. Thus this invention relates to a class of rotary vane pumping machines.
This class of rotary vane pumping machines includes designs having a rotor with slots with a radial component of alignment with respect to the rotor's axis of rotation, vanes which reciprocate within these slots, and a chamber contour within which the vane tips trace their path as they rotate and reciprocate within their rotor slots.
The reciprocating vanes thus extend and retract synchronously with the relative rotation of the rotor and the shape of the chamber surface in such a way as to create cascading cells of compression and/or expansion, thereby providing the essential components of a pumping machine.
Some means of radially guiding the vanes is provided to ensure near-contact, or close proximity, between the vane tips and chamber surface as the rotor and vanes rotate with respect to the chamber surface.
Several conventional radial guidance designs were described in the background section of pending U.S. patent application Ser. No. 08/887,304, to Mallen, filed Jul. 2, 1997, entitled "Rotary-Linear Vane Guidance in a Rotary Vane Pumping Machine" ('304 application). The '304 application describes an improved vane guidance means in order to overcome a common shortcoming of the conventional means of guiding the vanes, namely that high linear speeds are encountered at the radial-guidance frictional interface. These high speeds severely limit the maximum speed of operation and thus the maximum flow per given engine size.
In the improved sliding-vane pumping geometry of the '304 application, multiple vanes sweep in relative motion against the chamber surfaces, which incorporates a radial-guidance frictional interface operating at a reduced speed compared with the tangential speed of the vanes at the radial location of the interface. This linear translation ring interface permits higher loads at high rotor rotational speeds to be sustained by the bearing surfaces than with conventional designs. Accordingly, much higher flow rates are achieved within a given size pumping device or internal combustion engine, thereby improving the performance and usefulness of these machines.
However, even with the above advantages, efforts continue in order to further refine and enhance the performance of the rotary machine. One particular goal is to devise a rotor and stator cooling system that carries away the heat produced by combustion, compression or friction without interfering with any of the elements undergoing complex moving interactions in such a rotary vane pumping machine. For example, the rotor is moving inside the stator at the hottest portions of the rotary vane pumping machine, and the linear translation rings are moving in the end plates between the hottest portions of the engine and the cooling plates of the engine. Forming cooling channels in the rotor and stator, and moving coolant fluids through those channels without interfering with the machines operation, presents a unique and difficult challenge.
In addition, the rotor and stator cooling system should properly match the distribution of heat generated in a rotary vane pumping machine during operation. For an engine, the greatest heat is produced in the vicinity of the combustion residence chamber, while, for a pump, heat generation is expected to be greatest in a compression region of the stator.